Present investigations are directed toward understanding the intracellular function of cAMP. Isolation and characterization of cAMP dependent protein kinase and of the regulatory receptor and catalytic kinase subunits from adrenal cortical tissue are in progress. cAMP and protein kinase dependent ribosomal phosphorylation are being studied as a possible mechanism of hormonal regulation of protein synthesis. ACTH and cAMP control of RNA synthesis and of the RNA polymerase enzymes are being investigated.